Patent GB-480195-A (GB)
Title: Improvements in electric busbars
IPC: H02G5/06
Filed: 1936-10-30
Abstract: 480,195. Switchboards. GENERAL ELECTRIC CO., Ltd., SEARLE, A. F., and EVANS, F. Oct. 30, 1936, No. 29569. [Class 38 (v)] An arrangement of bus-bars suitable for extensible switchboards for installation in mines, comprises bus-bar chambers provided with apertured side extensions, an apertured connection box between each adjacent pair of bus-bar chambers, a flameproof joint between each busbar chamber and the adjacent connection box, and between each side extension and a complementary switchgear member, and a flameproof cover to each aperture in a side extension or in a connection box. The arrangement shown in Figs. 1, 2 comprises two bus - bar chambers 1, 2 having side extensions 3, 4, a connection box 5 between the chambers, an end closure 7 of cup or like shape, and a cable box 6, all of which parts are of cast iron. The flameproof joints 8 comprise flanges 10 constituting wide machined faces and screws 9. The extensions 3, 4 are provided with similar joints 8, constituted by flanges 35, with the switch boxes 11, 12, a cover being applied to the flanges when the boxes are removed. Two flat strip bus-bars 13, 14 of copper extending through apertures in insulating plates at the chamber - ends, have clamping screws 21 for leads 19, 20 passing through insulating plates 18 into the extensions 3, 4 and connected to terminals 31 of the switches in 11, 12. Over each screw 21 is an opening 22 closed by a plug 23, an insulating sleeve 24 being located over each bar opposite the screw 21 of the other bar. The bus-bars are positioned in the chambers 1, 2 by means of transverse screws 25 engaging the endplates, the leads 19, 20 are inserted and the chambers filled with insulating compound. Plates 18 are then put in position, and the chambers sent as units to the erectionsite. The bus-bars extend into box 5, where they are connected by links 27 consisting of bundles of bowed copper laminations which are each riveted together at the centre. Each box has a cover 30 which is removable to allow access to the links for sectionalizing, the box being accordingly left free of compound. Extensions 3, 4 also are left unfilled with compound and are provided with flameproof covers 32, 33. The cable is introduced into the part 36 of box 6 through a spout 37 and passed through an insulating plate 40 into sockets 41, the part 36 having a cover 42 and flameproof joint 8. The spout 37 is filled with compound by means of a filling- hole and air-vent which are afterwards closed by. plugs, at 38. Member 7 is provided for connecting the cable to the bus-bars by means of a switch, and also to permit extension of the gear. In Fig. 4, three switch-fuses 49.. 51 are connected to three bus-bar chambers 43 .. 45 and clamped to vertical channeliron supports 53 .. 55, with the chambers and connecting boxes 5 serving as transoms to tie the supports together. The switch-fuse 50 is smaller than the others and is accordingly supplied with a shorter bus-bar chamber. A modified cable box 6 comprises clamping rings or cones 58, for the cable-armouring, a ring or cone 59 for clamping a lead cone on to the cable, and common studs 60 and nuts 61 for clamping purposes. Plugs 38, 39 are provided for the vent and filling holes. The bus-bars are connected to the switch terminals by strips 56, 57, and terminal boxes with flameproof covers 65 .. 67 are provided at the remote ends. In Fig. 5 (not shown) is illustrated a conduit box for connecting a cable at right-angles to the bus-bars. The Specification refers also to a three-phase arrangement and to placing the switch-fuses below the bus-bar chambers.